1. Field of the Invention
The present invention relates to a system for the transmission of data in an installation comprising a plurality of devices distributed in a network of an information transmission medium.
The invention can be applied in an especially advantageous way, but not exclusively, to the field of the computerized management of domestic installations.
2. Description of the Prior Art
In the context of the computerized management of domestic installations, the devices of an installation generally comprise one or more control stations designed to receive instructions relating to the working of other devices such as the various appliances of the installation: television set, refrigerator, washing machine, radiator etc. These instructions may be, for example, ON and OFF instructions coming from a user or from the appliances themselves. In turn, the control station or stations send said appliances commands in the form of a message making it possible notably to obtain the desired modifications of operation. These commands are usually sent by means of various types of information transmission media such as carrier current, coaxial cables, twisted pairs, infrared radiation and RF links as well as optical fibers, ultrasonic links etc. Although its scope of application is very general, the invention relates more particularly to the carrier current medium, which is a favored medium for domestic installations.
The installation envisaged here may be of the localized intelligence type with only one control station receiving messages from appliances and mechanisms acting as enslaved stations and sending them towards other stations. In a distributed intelligence type of installation, each device can play the master or slave role by self-programming without going through the control station which only listens to the messages.
The appliances designed to be integrated into an installation for the computerized management of domestic appliances are generally designed by the manufacturers to work in a given configuration of reception defined, for example, by a command message transmission speed that depends on the type of appliance concerned. It is thus that heating appliances can work with a relatively low speed of 300 bauds, this speed being, however, quite insufficient for lighting devices which require a substantially higher transmission speed of at least 1200 bauds.
So as to enable these various appliances to coexist in one and the same network of an information transmission medium, steps towards bringing the different approaches into line with one another were initiated in 1991, and were aimed at stipulating a single transmission speed of 1200 bauds.
However, it is expected that, in the near future, devices, namely control stations or appliances, working at higher transmission speeds of 2400 bauds for example, are likely to be connected to installations that meet the present standard.